A controversy continues among both scientists and the public over the causal relationship between psychosocial stress and cancer development. While research in the area of stress and cancer has become increasingly sophisticated, the social and psychological context in which stress occurs has only recently begun to be explored. It has become clear that stress is a multifactorial phenomenon. Of the few studies in humans that have incorporated multifactorial approaches, many have been limited by the use of casecontrol or cross-sectional designs. None have employed a prospectivfe design. Further, most closely controlled studies have involved laboratory animals, limiting the ability to generalize findings. The predictive significance of psychoscial stress in relation to the risk of developing cancer, therefore, requires further exploration. To investigate the problem of the etiological role of stress in cancer, we will conduct a five-year prospective study of 2,500 long-term asbestos workers at very high risk of developing cancer. A comprehensive battery of questionnaires designed to assess psycholsocial stress will be administered annually. Data will be available on cancer mortality immunological status, demographic characteristics and the physical health status of this group through the cooperation of colleagues at the Environmental Sciences Laboratory at Mount Sinai School of Medicine. Cancer mortality and immunological status will be analyzed in relation to psychosocial stress using multivariate analytic techniques. The prospective design of this study will make it possible to obtain information on the predictive significance of stress in relation to cancer development and immunological changes. This research may provide important information concerning the relationship of stress to cancer that can be used for developing strategies for preventive intervention for the general population.